Dear Jim: I have thought about using a no-chemical ozone or salt purifier kit for my swimming pool to save on chemicals and reduce eye irritation from chlorine. Are these kits effective and do they use much electricity? – Mike G.

Dear Mike: People often are unsure about using ozone to purify swimming pool or spa water because of stories about harmful ozone smog in the air. Installing an ozone kit yourself instead of using strong chlorine chemicals is safe, natural and not related to ozone smog from cars.

Ozone gas is basically an active form of oxygen that reacts with bacteria, viruses, algae and other impurities in the water. At its low concentration levels in the water, it has no effect on your skin and eyes. Many municipal water purification plants use ozone to treat drinking water.

When the ozone gas dissolved in water contacts impurities, it oxidizes them as chlorine chemicals do. It also causes particles, body and suntan oils, etc., to clump so the filter can remove them more effectively.

Most ozone purifiers for pools and spas use only about 0.5 amperes when they are running. This is about the same amount of electricity a 60-watt light bulb uses. Since the ozone generator unit only runs when the filter pump is operating, the total amount of electricity used is not great.

The ozone kit is installed in the existing pool or spa filtration plumbing. There are several basic designs of ozone generators, but they all inject the ozone gas into the pool water through a small tube. The concentration of ozone gas is strongest at the point of entry for effective purification.

An ozone system is not actually “no-chemicals” because you still will need to keep a very low residual level of chlorine in the pool water. This is generally only about 20 percent as much chlorine as when no ozone is used.

The two basic types of ozone generators are ultraviolet and corona discharge. UV systems use a fluorescent light to create ozone as the sun does above the earth. CD units use an electrical arc inside a generator to create ozone as lightning does (the fresh smell after a storm).

Salt-type purification kits are used to create a steady level of chlorine in the water. They use only a small amount of electricity to break down the salt in the water into basically the same chemicals as adding chemical chlorine does.

The required salt concentration in the water is only about one teaspoon per gallon, less than the salt in a human tear. Pool water purified by this method is comfortable to swim in because the salt also softens the water. Once the pool water is charged with salt, the concentration stays fairly constant.

Write for (instantly download – www.dulley.com) Update Bulletin No. 759 – buyer’s guide of seven ozone and salt-type pool/spa purification system manufacturers (40 models) listing output levels, features, prices and installation instructions. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244.